HPP System Workflow Overview (Explore1, Edge1, Flight1)

This document provides a high level overview of the data collection and data upload workflow that enables creation of high precision, globally and locally referenced data with the Skycatch Explore1 High Precision Package System (Explore1 drone, Edge1 base station, and Flight1 mobile app).

We recommend reading through this document, and the User Manual, at least one week before your first flight; please reach out to us at support@skycatch.com with any questions or feedback.

1. Before Your Flight

1.1 Proper planning is critical.

The flight itself will likely only last a few minutes to an hour, but preparation beforehand ensures that repeat flights are not needed because the wrong coordinate system was used in the local base station observations, or because control points were incorrectly placed, or any multitude of small issues that could result in a day’s work being lost.

1.2 Established desired output

Talk to your data end users about how they will use the data. Data users will have different requirements for file types and accuracy. Be sure to understand Skycatch’s capabilities for supporting different file types and accuracy by reading through our support center for file types and accuracy.

1.3 Verify coordinate system at the project

Skycatch can export data in any possible coordinate system. If the data will be used in CAD, such as in the construction industry, users might want to use the data in “local coordinates” or “project coordinates”, which are defined by surveyors. Talk to an engineer or surveyor who has worked on site to see if a “site calibration” or “localization” file is available (usually .gc3 file). This will be required if the the data is not in an established coordinate system (e.g., State Plane, UTM, British National Grid, etc). More information on survey coordinate systems can be found here. Some common terms used and what you should ask the surveyor about are: Vertical datums, ellipsoid, geoid.

1.4 Determine exactly what you will map

Clearly define what area must be mapped for your project; it is especially important to know sensitive areas that should not be mapped. We recommend a buffer margin of an additional 10m around the desired boundary of your site. Talk to the project manager of the site in advance to agree on the exact mapping area. It is important to also clearly define the sensitive areas that should NOT be mapped (e.g. residential, etc.) You can always check out apps to see flight restrictions and no-fly zones (FAA or Airmap). Getting a markup in Google Earth (KML file) from the project manager helps provide a visual reference of the mapping area; our Flight1 mobile app supports KML file imports to help plan missions. You can learn more about this feature in our User Manual and online Support Center.

1.5 Establish how you will get high accuracy corrections

The Explore1 drone can record GPS data with survey precision, down to 2 cm (¾ inch). Achieving this accuracy requires establishing a base station in order to capture highly precise GPS correction data. For the best results, we recommend using the Skycatch Edge1 base station that comes with your HPP System. However, a different local base station (such as a Trimble or Topcon) can also be used. If you use a different local base station, you will need to generate RINEX files (local observation logs) so we can correct your data. Read more about generating RINEX files in our Support Center here. One final option for getting high accuracy corrections is using a network virtual reference station; please note that to set up a network VRS solution, you will need to contact Skycatch at least one week in advance of your first flight. Read more in the support center about “Using the NTRIP Logger For Network RTK Logging for Corrections (Evo3x and Explore1)”.

1.6 Plan your flights and resources

Coordinate your efforts with that of the onsite surveyor if needed (e.g., setting up control points, collecting static observations, confirming coordinate systems). Plan travel time and accommodate for weather. Do I have enough fully charged batteries? Do I have backups? Note that while our Explore1 drone and Edge1 base station are extreme weather tested, it is always good to be cautious when inclement weather can affect flying a mission.

1.7 Regulatory

Confirm you have all the required legal and regulatory items covered. Am I legal to fly? Am I insured? Do I need and have a Part 107 pilot license? Do I have appropriate airspace permissions? Are there other airspace considerations? Are there stationary or moving flight obstacles I have been made aware of? AirMap is an app that has most airspace restrictions and should be referenced before you get to the site. If the flight is inside controlled airspace, a waiver from the FAA can take weeks.

1.8 Confirm kit readiness

The day before your flight, charge all items in the kit including drone batteries, tablet, and controller. Perform a visual check using the included quick start guide to confirm that all kit items are present before heading to your site to fly. Familiarize yourself with the Flight1 app. With the propellers off of the drone, it is a good check to power-on all parts of the HPP system to ensure that communication between the Explore1 drone, remote controller, and Flight1 app is healthy. Healthy communication is indicated by green lights at the top of the drawer in Flight1 and a green light on the remote controller.

2. On Site

2.1 Confirm deliverables and actions from stakeholders

Meeting with the site engineer, surveyor, BIM team, and/or project manager. Confirm the surveyor will give you corrections and/or control points, and coordinate system details (localization). Confirm that the site engineers and BIM team are using the same drawing coordinate system as the surveyor. Confirm HSEQ has approved flights.

2.2 Review logistics plan with project team

Ask the project team for a site tour. Identify all relevant obstacles and potential risks including terrain and equipment on site. Identify ditch (emergency landing) locations, no fly zones, and spotter locations if required. Identify takeoff and landing areas, GCP and/or checkpoint areas (here are a Skycatch’s control points resource guides), and target areas to set up a base station (if that will be used).

2.3 Place control points

The Skycatch RTK system significantly increases the accuracy of 3D data collected without the need for control points. However, many clients and applications still require the use of GCP’s or checkpoints to demonstrate the validity of the data. Remember that there is a difference between GCPs and checkpoints, so you should plan accordingly. With quality RTK data, 4 GCPs and/or 3 checkpoints are sufficient to properly locate and assure quality outputs. These linoleum tiles make cheap and easy to use targets. We also have custom QR code control point patterns that you can print and use.

Important usage note: Record the position of these control points in local coordinates.

2.4 Start a local observation or Network RTK log (this step only applies if you are not using a base station)

In order to apply accuracy corrections to your data, we must always be provided observation files; these files must either come from a base station or from a VRS correction. If you are not using a base station, you will now need to either:

If you plan to upload multiple flights to Skycatch for processing as a single area, you must use only one correction log (observation) per upload. For example, if you plan to fly in the morning, break for lunch, and continue flying the same site after lunch, you will need to keep the log running and submit one observation for the entire dataset. This is the case for both local base station and VRS corrections.

It is not required to fly missions with base stations. If you fly a mission(s) without a base station, remember that the data you upload from that mission(s) will not have PPK correction data applied to it, and will have standard GPS accuracy.

2.5 Plan flights and execute safely

Plan your flights using the Skycatch Flight1 app based on the end user’s desired resolution; most notably, altitude of your flight will change in order to accommodate resolution. Please note that while we display terrain following as a feature in the Flight1 app, it is not currently available to use; this feature will be available later in 2018.

2.6 During flight

You are the person in control for this flight. You are responsible for ensuring that the flight is operated in a safe and legal manner, while still collecting the data that is required. Don’t be afraid to stop the mission if you see any obstacles or things that may go wrong; to do this, you can flip the switch on the remote controller from “F” to “P” (for Explore1; other DJI models may have different switch positions) and start steering with the remote controller’s joysticks, or you can tap “Pause mission” on the Skycatch Flight1 app to put the Explore1 into a hover while you re-assess the situation and plan next steps.

2.7 After landing

Make sure to power off the drone and remove the SD card. Then remove the propellers, take the drone’s battery out, and store all equipment back in the case.

If you are using the NTRIP logger to log observations and this was your last flight of the day, please make sure you stop the NTRIP logger before uploading your data.

3. After Your Flight

3.1 Transfer all photos and precision files for processing

Using the SD card converter in your HPP System Kit, transfer ALL files for each mission. We automatically generate folders in the drone’s SD card for photo files and drone RTK files -- one folder per mission, and each flight in the mission gets an individual subfolder. Remember that drone RTK files and base station RINEX files are different. After you transfer the files from the drone, transfer the files from your base station, if you used one. If you used Skycatch cloud NTRIP logging, only the drone files are needed for processing (we automatically retrieve and apply the NTRIP files in the cloud). If you used Edge1 as the base station, the base log files are also automatically applied during processing on Edge1.

3.2 Use web uploader to verify mapping area

To upload photos via https://upload.skycatch.com, drag them from local directory into the browsing box or browse for photos in the Viewer. After the upload is complete, you can review the location of the photos on the rendered map to validate correct location and that there are no gaps. Read more about uploading your images in our support center: “How to Upload your Images for Processing”.

3.3 Select site

In this step of the upload process you can modify and change the following: date, site, coordinate system, plane, and GEOID model. Please read the “Select Site” portion of our support article “How to Upload your Images for Processing” to understand this step.

3.4 Add precision files and information

In this step of the upload process you can add precision files to help us more accurately apply corrections to your data; this will ensure the highest quality output of your 2D and 3D models. You can add TP3 files, .txt files for control points, RTK files, RINEX files if you used an RTK base station, and base station antenna information. Please read the “Add Precision Files” portion of our support article “How to Upload your Images for Processing” to further understand this step.

A note about entering antenna information: The information you provide should be in your local projection, if it’s a known coordinate system (e.g. NAD83/CA Zone3 you’d click “Use GPS position” in the uploader). For an arbitrary projection, use WGS84 and enter information for using height above ellipsoid for GPS position; also, the elevation should include the height of the antenna phase center.

3.5 Review dataset before processing

In this step of the upload process, you can review all files added before sending it to our processing pipeline. Take a look at the map one last time to make sure locations of photos and precision files make sense. After you upload, you’ll receive a confirmation email. Please read the “review” portion of our support article “How to Upload your Images for Processing” to further understand this step.

3.6 Using Edge1 base station to process and manage data

For more detailed instructions, please refer to our User Manual. Before your first flight, you will have to do the following:

Add an RTK account

Obtain a flash drive for processing the data (you can use the SanDisk iXpand drive we provide you in the kit)

Charge your Edge1 base station

Important usage notes:

If you want to use the Edge1 base station to process and manage data, you must turn it on and set it up before you fly your mission. We recommend turning it on at least 5 minutes before you start your mission.

You do not need to use upload.skycatch.com to upload and process your data if you already use the Edge1 base station to process your data.

4.Viewing and Modifying Data in the Viewer

4.1 What will be available and when

Turnaround times for map processing in the cloud can vary depending on the size of the site and number of photos that have been submitted. However, for normal datasets, cloud processing times tend to be approximately:

# of photos

Turnaround times in hours (estimated)

Less than 300 photos

1 to 3 hours

400 photos

up to 4 hours

500 photos

up to 5 hours

600 photos

up to 6 hours

700 photos

up to 8 hours

800 to 1500 photos

up to 24 hours

Over 1500 photos

up to 48 hours

Please always contact us in advance if you plan to upload a dataset with more than 1,500 images. While our processing pipeline does accommodate a dataset with more than 1,500 images, we may ask you to split your dataset into a couple uploads.

Once processed, you can view your 2D and 3D models by logging into your account at app.skycatch.com. We also offer all outputs through a cloud storage system, in partnership with Box, so you can download your data at any time in various output formats, directly to your PC, and they are also automatically placed on Box.com. See the formats available in the screenshot below:

4.2 Analyzing your data

You can then add annotations, measurements, overlays, and notes to your 2D and 3D models. Please note that the ability to delete overlays is still in beta and will soon be released. For now, if you need to delete an overlay, please contact us at support@skycatch.com.